In the proposed work, the principal investigator will study the following: 1) he will study the enzymatic properties of carboxypeptidase F (CPF) and compare those to Carboxypeptidase E (CPE) using enzymes purified from bovine pituitary and rat brain. He will expand the studies of substrate specificity and including the study of cleavage of natural occurring peptides. In this case, there will be a strong effort to identify the specific cleavage products using both HPLC analysis and a modification of mass spectrometry called matrix assisted laser desorption ionization time of flight mass spectrometry (MALDITOF-MS). The second specific aim is to determine the distribution of CPF. This will be done initially based on enzymatic activity, this will be followed by studies using antisera raised to CPF and finally by studies of mRNA expression once the cDNA clone is available. Specific aim 3 is the proposal for actually cloning the full length CPF cDNA. This is based primarily on a PCR strategy taking advantage of the known N-terminal sequence and known homologous regions in other CP enzymes. Finally, the principal investigator will evaluate whether CPF is regulated in the fat/fat mouse both at the enzymatic, protein and RNA levels. This will include studies of mice of different ages, since the fat/fat mouse shows different degrees of hyperglycemia at different ages.